Aside from closing the loophole, states could also rein it in by requiring contributors to show their federal tax return to prove that they aren't "double-dipping," Davis said.
Betsy DeVos: School vouchers part of tax overhaul discussions →
"That's not charity. That's just helping facilitate the movement of funds. These so-called donors are really like middlemen," Davis said. "They're not making a financial sacrifice."
DeVos say school vouchers part of tax overhaul discussions →